Process for producing 1, 3, 3-trichloropropene-1 from allyl chloride



Unite This invention relates to a process for making a chlorinated olefin, principally 1,3,3-trichloropropene-l, by di- -rect chlorination of another chlorinated olefin, principally allyl chloride, in a single stage, according to the following The process may be summarized as follows. The starting chlorinated olefin is preheated up to a temperature close to or immediately below the reaction temperature (400 C. and above) and is then admired with chlorine. This preheating is followed by immediate reaction, and thereafter by immediate' cooling, with the absorption of -the hydrochloric 'acid formed in the reaction. This is immediately followed by rectification of the products obtained, to separate said trichloropropene from the less chlorinated products. The latter are recycle to the reaction.

TheV process is illustrated in the flow diagram of FIG. 1 of the accompanying drawings. Chlorine is supplied at A and fresh allyly ychloride is fed from B to the reaction stage I', the products `of which are passed to the condensation stage designated lil. The hydrochloric acid remains in the gaseous state, being passed at O to the absorption stage VI to which water is fed 'from C. Aqueous hydrochloric acid solution is discharged at X. From stage Il the reaction product is passed to the rectification stage Ill, from which allyl chloride and a portion of dichloropropone are recycled through Condit H to stage i. The remaining dichloropropene, trichloropropene and heaviest fractions are in the meanwhile passed through pipe K to the vacuum rectification stage IV. From the latter stage the remaining dich'loropropene is recycled at M to stage I, while trichloropropene and the heaviest fractions, designated N, are passedv toV stage V for further vacuum rectification. The heaviest fractions are discharged at Y, commercial trichloropropene being obtained as end product Z.

FlG. 2 is a more detail-ed flow diagram, a symbolic representationl of the apparatusV equipment being provided therein. The third rectification stage V of FIG. 1 is not shown' in FIG. 2, but obviously may be added. FIG. 3 shows a variantV of FIG. 2. Like reference characters found in FIGS. l, 2 and 3 designate the same operations and apparatus.

With reference toFlG. 2, fresh allyl chloride and the recycled portion coming from the rectification are fed to evaporator F1. The vapors here developed are preheated in preheater F2, being then mixed with chlorine from A and introduced into the chlorination reactor Ai. The reaction takes'place in reactor Al in the presence of a large amount of recycledchlorinated olefins so as to have present a highy molar ratio of chlorinated olefins to chlorme.

The reaction Aproducts are condensed in cooler F3, a condenser, the hydrochloric acid being separated from the chlorinatedoletins in vessel SR2 and absorbed in water in column C3.

The liquid chlorinated olefins are then passed to the rectification column Cl by pump PC2. At the top of this column the unreacted allyl chloride and dichloropropone are separated'and returned by pipe H and pump States @arent 'FCl to the reactor Al. From the bottom of column Cil the trichlorinated product is obtained, together with a small amount of dichloropropene and products having 'a higher boiling point than trichloropropene. This mixture is fed through conduit K and vessel SRS to the no'ncontinuous rectification column C2 which yields dichloropropone as a top. The latter is sent through pipe M `and vessel SR1 to the reactor, by pump PCi. Trichloropropone having a content of 1,3,3 isomer Varying from 65% to 75% of the trichlorinated product is removed at Z. The heaviest fraction is removed at Y.

From the fiow sheet of FiG. 2 it is evident that, to the reactor Al, a mixture of fresh allyl chloride and of recycled chlorinated products is fed from the two rectification columns. This is also true of FIG. l1. Under normal operating conditions this feeding mixture consists of allyl chloride and dichloropropene. The conditions are thus predetermined so that the number of allyl chloride mois transformed into dichloropropene is equal to the number of dichloropropene mois which are transformed into trichloropropene.

it has been found that at the temperature of 470 to 490 C. the reaction product is subject to decomposition, to produce carbon residues. It is therefore necessary to limit to a minimum the time of stay at a high temperature, namely to that needed for completing the reaction.

With this in View, in a further embodiment of the process, the flow-diagram shown in FlG. 2 is modified as shown in PIG. 3 to provide quick cooling of the reaction gases. Namely, the outlet of pump PC2 is also connected to the outlet Zone of reactor Al for the purpose of recycling a large quantity of liquid reaction products at a temperature of 30 C. This injection into the outlet zone of the reactor produces a quick and effective cooling, bringing the temperature down to below C. within a very short time.

The present invention is characterized by the following significant features:

(a) The chlorination of allyl chloride to trichloropropene is carried out in a single reaction stage and in the presence of a total recycle of the products lighter than trichloropropene, the working conditions being such that the number of mols of allyl chloride transformed into dichloropropene is equal to the number of dichloropropene mois transformed into trichloropropene, as stated above.

(b) Preheating of the chlorinated olefins is carried out up to a temperature close to the reaction temperature. Any Contact between the olefins and chlorine at low temperature is avoided, when effecting the admixing with chlorine.

`(c) A cylindrical reactor is used, provided with a hemispheric joint in the upper part connecting the Yreactor to the mixer. Effective mixing of the reactants is obtained by equidirectional parallel or tangential collision of the two gaseous streams at high speed.

*(d) Immediate and effective cooling of the reaction products is carried out in order to avoid their decomposition resulting in a carbon deposit.

The temperature range' has been investigated. A special study was made of the reaction at temperatures in the range between 470 and 490 C., with Space velocities varying from 1000 to 3000 Nl/lh, preferably from 1050 and 2600 Nl/lh, and with a molar ratio of chlorinated olefins to chlorine varying from 3.5 to 6.0 preferably from 3.8 to 5.9.

It has been found that the best reaction conditions are at 490 C. with a space velocity of 2,600 Nl/lh and a molar ratio of chlorinated olefins to chlorine of 4.8. Under these conditions the yield of trichloropropene, namely the fraction which under a pressure of 50 mm. Hg (absolute) boils at between 45 and 65 C. and prevailingly consists of 1,3,3-trich1oropropene-1 plus a small amount of its isomers, in respect of allyl chloride, was 70%.

This result is surprising for several reasons. It was eX- pected that a great decrease in yield would occur due to side reactions. Such decrease was also to be expected due to the fact that the operation is carried out in the presence of undesired isomers, and the fact that two different reactions take place in the same reactor, namely the transformation of allyl chloride into dichloropropene and the further reaction of the miXture of recycled material comprising dichloropropene. It was surprising to nd that when tests were carried out in two distinct stages,l namely by iirst producing dichloropropene from allyl chloride, separating the useful isomer of dichloropropene from the reaction mixture, and then transforming the purified dichloropropene into trichloropropene, the yield of 1,3,3 isomer in respect of the starting allyl chloride is lower than that obtained by the one-step process of the present invention.

The invention is illustrated by the following examples. They were selected as the most significant ones, in order to show the influence of the variables upon the course of the process and upon the respective yields. These embodiments are in no sense to be considered as limitative.

Example 1 Reaction temperature C 490 Chlorine ow rate g./h 1,108 Flow rate of the chlorinated olens fed to the reactor g./h 7,000 Composition of said mixture:

Allyl chloride ..-percent by weight 44.7 Dichloropropene do 55.3 Chlorinated olens/ chlorine molar ratio percent by weight 4.8 Space velocity Nl/lh 2,600 Products obtained at the outlet of the reactor a /h 8,100 Composition of these products:

Hydrochloric acid percent by weight 7.5 Allyl chloride do 30 Dichloro-propene do 48 Trichloropropene do 11.5 High-boiling do 3 Consumption of fresh allyl chloride g./h 699 Trichloropropene obtained g./h 924 Hydrochloric acid obtained g./h 612 High-boiling products obtained g./h 203 Yield of the process percent 69.5

Example 2 Reaction temperature C 490 Chlorine flow rate g./h 880 Flow rate of the chlorinated olens fed to the reactor g./h 5,600 Chlorinated oleiins/ chlorine molar ratio 4.9 Space velocity Nl/lh-- 1,500 Products obtained at the outlet of the reactor g./h 6,470 Fresh allyl chloride consumed g./h 694 Trichloropropene obtained g./h 750 Hydrochloric acid obtained g./h 542 High-boiling products obtained g./h 207 Yield of the process percent 56.8

Example 3 Reaction temperature C 470 Chlorine ow rate g./h 888 Flow rate of the chlorinated olens fed to the reactor g/h-.. 5,600 Chlorinated oleiins/ chlorine molar ratio 4.9 Space Velocity Nl/lh 1,500 Products obtained at the outlet of the reactor Fresh allyl chloride consumed g./h 614 Trichloropropene obtained g./h 717 Hydrochloric acid obtained g./h 472 High-boiling products obtained g./h 207 Yield of the process percent 61.4

Example 4 Reaction temperature C 470 Chlorine flow rate g./h 1,090 Flow rate of the chlorinated oleins fed to the reactor g./h 5,400 Chlorinated olens/chlorine molar ratio 3.8 Space Velocity Nl/lh 1,500 Products obtained at the outlet of the reactor g./h 6,480 Fresh allyl chloride consumed g./h 720 Trichloropropene obtained g./h 847 Hydrochloric acid obtained g./h 585 High-boiling products obtained g./h 234 Yield of the process percent 61.8 Example 5 Reaction temperature C 470 Chlorine flow rate g./h 754 Flow rate of the chlorinated olens fed to the reactor g./h 5,900 Chlorinated olens/chlorine molar ratio 5.9 Space velocity Nl/lh-- 1,500 Products obtained at the outlet of the reactor g./h 6,650 Fresh allyl chloride consumed g./h 530 Trichloropropene obtained g./h 600 Hydrochloric acid obtained g./h 406 High-boiling products obtained g./h 210 Yield of the process percent 59.5

Example 6 Reaction temperature C 470 Chlorine flow rate g./h 612 Flow rate of the chlorinated olens fed to the reactor g./h 4,000 Chlorinated olelins/ chlorine molar ratio 4.9 Space velocity Nl/lh 1,050 Products obtained at the outlet of the reactor g./h 4,600 Fresh allyl chloride consumed g./h 440 Trichloropropene obtained g./h 478 Hydrochloric acid obtained g./h 377 High-boiling products obtained g./h 117 Yield of the process percent 57.3 Example 7 Reaction temperature C 470 Chlorine flow rate g./h 1,053 Flow rate of the chlorinated olefins fed to the reactor g /h 7,000 Chlorinated olens/chlorine molar ratio 4.9 Space velocity Nl/1h 2,600 Products obtained at the outlet of the reactor g./h 8,050 Fresh allyl chloride consumed g./h 676 Trichloropropene obtained g./h 785 Hydrochloric acid obtained g./h 546 High-boiling point products obtained g./h 243 Yield of the process percent 61 From the above examples, it appears that 1,3,3-trichloropropene-l is obtained by chlorination of allyl chloride in conditions of equilibrium between the amount of allyl chloride fed and the amount of dichloropropenes fed by total recycle, the allyl chloride/dichloropropenes molar ratio of the feed being between 1.1 and 1.25, and the chlorinated `olelins/ introduced chlorine ratio being between 3.5 and 6, at a space velocity of between 1000 and 3000 Nl/lh. The preferred latter ratio is 3.8 to 5.9. The preferred space velocity is between 10.5.0 and 26.0.01

In the specification and claims, the symbol Nl/lh is adopted to denote: litres of gas calculated at 0 C. and 760 mm. Hg, per litre reactor` volume capacity per hour.

The amount of dichloropropene present in the reaction mass appears to be substantially constant for any or the equilibrium conditions exempliiied.

Although the preferred reaction temperature is from 470 C. to 490 C., the process may be carried out, although less advantageously, in the range from 400 to 550 C. With a reaction temperature range of from 400 to 550 C., the corresponding range of preheating temperatures becomes from 300 to 450 C.

We claim:

l. A continuous process for preparing a product which is prevailingly 1,3,3-trichloropropene-1, comprising reacting chlorine with allyl chloride at a temperature of at least 400 C., `fresh allyl chloride being continuously fed to the reaction zone, subjecting the reaction mixture to immediate chilling to below 150 C., removing the hydrogen chloride produced in the process, separating trichloropropene from the unreacted allyl chloride and the dichloropropene produced in the process, and recycling the dichloropropene and said unreacted allyl chloride to the reaction Zone, said chlorinating being carried out in the presence of a substantially total recycle of the organic products lighter than trichloropropene, the molar ratio of chlorinated olens to chlorine in the reaction zone being between 3.5 and 6.

2. A process according to claim 1, characterized in that the fresh and recycled starting chlorinated oleins are preheated up to a temperature close to the reaction temperature before mixing them with chlorine, to minimize reaction between chlorine and olens at below said reaction temperature.

3. A process according to claim 1, characterized in that the chlorination reaction is carried out at temperatures between 470 and 490 C.

4. A process according to claim 1, characterized in that the reactants are introduced into the reaction at a space velocity of between 1000 and 3000 Nl/ lh.

5. A process for making 1,3,3-trichloropropene-1, comprising reacting a mixture of chlorine and allyl chloride in a reaction zone which is at a temperature of at least 400 C., immediately chilling the exiting reaction products to a temperature below 150 C., separating allyl chloride and at least part of the dichloropropene produced in the reaction from the 1,3,3-trichloropropene-1, recycling the said allyl chloride and dichloropropene to the said reaction zone to react with fresh chloride and fresh allyl chloride, passing remaining dichloropropene and l,3,3-trichloropropene-1, to a rectiiication zone to separate dichloropropene from `said trichloropropene, and passing the latter dichloropropene to said reaction zone, the molar ratio of chlorinated oletins to chlorine in said reaction zone being at least about 3.5.

6. A process for making 1,3,3-trichloropropene-1, comprising separately preheating chlorine and allyl chloride, mixing the preheated chlorine and allyl chloride by impinging streams of the latter upon each other, immediately thereafter passing the mixture into a reaction zone which is at a temperature of at least 400 C., immediately chilling the exiting reaction products to a temperature below 150 C., separating gaseous hydrogen chloride from other reaction products by condensation of the latter, then subjecting the reaction products to rectification to separate allyl chloride and at least part of the dichloropropene produced in the reaction from the 1,3,3- Y

trichloropropene-l, recycling the 'said allyl chloride and dichloropropene to the said reaction zone to react with fresh chlorine and fresh allyl chloride, passing remaining dichloropropene and 1,3,3-trichloropropene-1 from said rectiication to a vacuum rectification to separate dichloropropene from said trichloropropene, and passing the latter dichloropropene to said reaction zone, said chilling of exiting reaction products being carried out by introducing cold liquefied organic products of the reaction thereinto the molar ratio of chlorinated oletns to chlorine in said reaction zone being atleast about 3.5.

7. The process of claim 6, the reaction being carried out at from about 470 to about 490 C., the molar ratio of chlorine to chlorinated oleins being between 3.5 and 6.

8. The process of claim 7, the space velocity being between 1000 and 3000 Nl/lh.

9. A continuous process for preparing a product which is prevailingly l,3,3-trichloropropene-l, comprising reacting chlorine with allyl chloride at a temperature of at least 400 C., fresh allyl chloride being continuously fed to the reaction zone, subjecting the reaction mixture to immediate chilling to below 150 C., removing the hydrogen chloride produced in the process, separating trichloropropene from the unreacted allyl chloride and the dichloropropene produced in the process, and recycling the dichloropropene and said unreacted allyl chloride to the reaction zone, said chlorinating being carried out in the presence of a substantially total recycle of the organic products lighter than trichloropropene, the molar ratio of chlorinated olens to chlorine in the eaction zone being between 3.5 and 6, said chilling being carried out by introducing chlorinated olefins resulting from the reaction in cold, liqueiied form.

l0. The process defined in claim 9, the reaction being carried out at about 470 to 490 C., at a space velocity ot about 1050 to 2600 liters of gas, calculated at 0 C. and 760 mm. mercury pressure, per liter of reaction volume capacity, per hour.

l1. A process for making 1,3,3-trichloropropene-1, comprising separately preheating chlorine and allyl chloride to a temperature immediately below reaction ternperature, mixing the preheated chlorine and allyl chloride, reacting the mixture in a reaction zone which is at a temperature of at least 400 C., immediately chilling the exiting reaction products to a temperature below 150 C., separating gaseous hydrogen chloride from other reaction products by condensation of the latter, then subjecting the reaction products to rectification to separate `allyl chloride and at least part of the dichloropropene produced in the reaction from the 1,3,3-trichloropropene-l, recycling the said allyl chloride and dichloropropene to the said reaction zone to react with fresh chlorine and fresh allyl chloride, passing remaining dichloropropene and 1,3,3-trichloropropene-1*from said rectiication to a vacuum rectification to separate the dichloropropene from said trichloropropene, and passing the latter dichloropropene to said reaction zone, so that the reaction is carried out with substantially total recycle of dichloropropene, the molar ratio of chlorinated oletns to chlorine in said reaction zone being at least about 3.5.

l2. A process for making 1,3,3-trichloropropene-1, comprising reacting a mixture of chlorine and allyl chloride to produce dichloropropene and said trichloropropene, immediately chilling the exiting reaction products to a temperature below C., separating unreacted allyl chloride and the dichloropropene produced in the reaction from the 1,3,3-trichloropropene-1, and reacting the said unreacted allyl chloride and dichloropropene with chlorine and fresh allyl chloride to produce said trichloropropene, the molar ratio of chlorinated olens to chlorine in said reaction zone being at least about 3.5, the number of allyl chloride mols transformed into dichloropropene being substantially equal to the number of mols of dichloropropene transformed into trichloropropene. 

1. A CONTINUOUS PROCESS FOR PREPARING A PRODUCT WHICH IS PREVAILINGLY 1,3,3-TRICHLOROPROPENE-1, COMPRISING REACTING CHLORINE WITH ALLYL CHLORINE AT A TEMPERATURE OF AT LEAST 400*C., FRESHALLYL CHLORIDE BEING CINTINUOUSLY FED TO THE REACTION ZONE, SUBJECTING THE REACTION MIXTURE TO IMMEDIATE CHILLING TO BELOW 150*C., REMOVING THE HYDROGEN CHLORIDE PRODUCT IN THE PROCESS, SEPERATING TRICHLOROPROPENE FROM THE UNREACTED ALLYL CHLORIDE AND THE DICHLOROPENE PRODUCT IN THE PROCESS, AND RECYCLING THE DICHLOROPROPENE, AND SAID UNREACTED ALLY CHLORIDE TO THE REACTION ZONE, SAID CHLORINATING BEING CARRIED OUT IN THE PRESENCE OF A SUBSTANTIALLY TOTAL RECYCLE OF THE ORGANIC PRODUCTS LIGHTER THAN TRICHLOROPROPENE, THE MOLAR RATIO OF CHLORINATED OLEFINS TO CHLORINE IN THE REACTION ZONE BEING BETWEEN 3.5 AND
 6. 